Introduction about Test Bench
Sometimes we need to set up a virtual system or network to guarantee its consistency and reliability in order to test the functionality of an application close to that in a real world scenario. Such activity is done with the help of the test bench to simulate the design under test and the unit under test.
A test bench can be defined as a set-up that makes it possible to test an application by replicating the use of the same in the real world. When checking applications, a code file runs on the computer to verify the functionality of the device.
The need to check and confirm the functionality of the network is really relevant with a growing demand for high-end digital systems. The Definition Language (HDL) language of the hardware is used to generate a recorded, repeatable series of test reports that can be used through several simulators. Verilog and VHDL are two very popular HDLs.
Our evaluation approach also focuses on identifying device vulnerabilities. This method limits the complexity of the program, so the research bench offers a solution by encouraging users to do more rigorous testing and fully understand how it works. It is possible to create a test bench using either of the following methods:
Text Editor- Recommended to test very complex designs, enabling to use the functionality available in HDL. Offers a great deal of versatility in project maintenance which aims to achieve consistent and accurate results.
Xilinx Test Bench Waveform Editor- Recommended for use by comparatively new users for less advanced simulation activities.
VHDL: The Ada programming language has its origins in this language. VHDL stands for VHSIC Hardware Definition Language mainly used in digital computer architecture. This is a language that is heavily typed.
Verilog: This is again an HDL used in modern digital systems, analog circuits and mixed signal circuits. Verilog is a language that is loosely written, but it has an appropriate notation.
System Under Test (DUT): A system being evaluated can be considered simply as a copy of the actual design or as a reflection of a design’s behavior.
Components of Test Bench:
Output –This requires the work performance criteria. Essentially, this is the research bench entry criteria.
Input-It comprises of the exit parameters or we can claim the result at the end of the test bench.
Procedures for –processes to convert inputs to outputs.
Test procedures- These are the processes that decide if the production meets the standard needed.
Types of Test Bench:
Stimulation Only-Contains only the vehicle under evaluation that includes the stimulation driver and the specification but does not include any proof of the tests.
Full Test Bench-This research bench contains the stimulation unit, the right tests and comparative outcomes.
Simulator Specific- The name suggests a simulator-specific configuration for the test bench.
Hybrid research bench –This is a combination of more than one test bench type techniques.
Quick test bench-Optimizing a test bench’s pace. This is written in such a way that a simulation has the best speed.
Summary: Usually a code file is performed in a simulation-specific language during the test bench phase. Let’s now use Verilog as an illustration in the test bench sense. The code is written to suit the device requirements before we start working on a verilog script.
module basic_and #(parameter WIDTH = 1)(
input [WIDTH-1:0] a,
input [WIDTH-1:0] b,
output [WIDTH-1:0] out
);
assign out = a & b;
endmodule
The documentation above is essentially to develop a better understanding of how it behaves like a verilog application node. Such code takes as inputs only a few variables, ANDs them, and generates an output. Now if you want to make sure the module produces the desired performance, then to verify its functionality, we need to compose a test bench connected with the module.
module basic_and_tb();
reg [3:0] a, b;
wire [3:0] out;
basic_and #(.WIDTH(4)) DUT (
.a(a),
.b(b),
.out(out)
);
initial begin
a = 4’b0000;
b = 4’b0000;
#20
a = 4’b1111;
b = 4’b0101;
#20
a = 4’b1100;
b = 4’b1111;
#20
a = 4’b1100;
b = 4’b0011;
#20
a = 4’b1100;
b = 4’b1010;
#20
$finish;
end
endmodule
Typically a research bench starts with the program name and a system has no inputs or outputs, it is a null device itself. A clock pulse initiates an event and the clock signals are preceded by the execution of the machine. Precisely this is how a test bench is done.
